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Solid State Relays

This great round-up of the solid-state relays currently on the market was posted by MikeCasino to TheHammondZone.


Relays Dedicated to a Leslie Family (either 122 or 147)

A) EIS (Mark IIa-122 & Mark IIa-147)

Fast stop slow switching method (extra board for 122 using any S.P.D.T. center off switch ), eliminates the 12AU7 switching tube in the 122 family, standard cabling compatible with stock Leslies using the tremolo / chorale switching method but not compatible with stock Leslies using the tremolo / stop / chorale switching method in stop mode (the stock amp will still remain on fast when you have the switch on stop). Mounting location is in place of the mechanical relay. To use the stop function, a tremolo / stop / chorale switch is used in place of the tremolo chorale switch. The .1mfd cap removal is required.

Switching scheme: apply a common-mode DC bias on the input of greater than 25 volts for slow; apply zero volts for fast; apply from 9 to 13.5 volts for off. Note that if you plug the relay into a stock control kit for a 122, you'll get normal two-speed (fast/slow) operation.

Vendor comments

The Mark IIa Solid State relays for Leslie 122 and 147/251 provide noiseless, quick and extremely reliable motor control. Installation is simple - they are 100% compatible with existing Leslie control circuits and no additional wiring is required from the console. All necessary materials for installation (except the three position switch) and complete instructions are provided. As a bonus for 122 users, switching time with this device is virtually as fast as the 147. Our 122 relay also makes converting 147 amplifiers to 122 specs a snap. The relay control tube is eliminated, as are a number of other components! For the 122 version, an optional, low cost ($2.00) board interfaces with the TREK II TS2-3, or any S.P.D.T., center off switch. The 147/251 version will interface with the TREK II TS2-3 as well. The 122 version will operate on any voltage from 80 - 300 and any frequency from 25hz to 80hz. The 147/251 version operates from 80 - 240 vac. Either will operate on any frequency encountered. If the console switching is modified for tremolo-off-chorale operation, all Leslies used must be equipped with EIS relays. Although no damage to a stock Leslie will occur, switching will be erratic.

All of our solid state relays are totally compatible with legacy Leslie switch kits. They will function exactly as the stock relay, minus noise and clicks and last virtually forever. If you opt for 3 speed operation, all Leslies must have our relay, however, if used as a replacement two-speed relay, go ahead and run them together.

The interface board for the 122 version allows the use of the TREK II TS2-2, ETS2-2, or any S.P.D.T. center off switch to obtain Chorale - Off - Tremolo. The 147 version has software that makes this board unnecessary.

Either version can provide Chorale - Off - Tremolo with a three position switch as used in the Main - Ensemble - Echo Leslie switches. Instructions and the necessary diode are included with the relay.

In the 122 version, a 33V to 36V 1 watt zener diode may also be added to stock Leslie 8000 style kits to decrease switching time. Stop mode requires a 12V zener diode in switching circuit.

147 3 speed version: Functionally, just like the 122 version.  When first powered on, the relay responds to 0v for Tremolo and 120v (or 240v on export units) for Chorale.  This makes it compatible with legacy switching kits.  If a three-position switch is used, a diode is added to provide 1/2 wave DC. The processor has a "learning" mode to detect 1/2 wave and configure for three-speed operation, 120 (240) for chorale, 0v for stop and 1/2 wave for Tremolo.

If you install the tremolo control circuit in the pre-amp, use a 33V - 36V 1 watt zener diode to ground, in parallel with the 47K, 1W resistor. The cathode (banded) end goes to the resistor junction. This limits the switching voltage to the zener value, prevents the momentary off condition when switching from chorale to tremolo and greatly decreases the switch response time, almost as fast as a 147 (A.C.) relay. It also prevents core saturation in the output transformer.


B) Hamptone (HT SSR-122 & HT SSR-147)

Fast slow switching method standard cable, compatible with stock Leslies. Eliminates the 12AU7 switching tube in the 122 family. Mounting location is in place of the mechanical relay. The .1mfd cap removal is not required.

Vendor comments

Are you tired of listening to that nasty "click" and "snapping" sound you get every time you switch your Leslie® from slow to fast? Replace that old and noisy mechanical relay with a silent Hamptone solid state relay. Unlike the cheaper and simpler designs, the Hamptone solid state relays are optically isolated to insure safe, reliable operation and will also work properly if using a Hamptone MK1B Motor Control. The Hamptone solid state relays are available for the 147 type and the 122 type Leslies®. The Hamptone relay circuit employs two independent logic controlled solid state switches, one for the fast motors and one for the slow. The solid state switches are designed such that they only open or close when no current is flowing through the motors. This also eliminates the possibility of motor switching noise coupled into the audio circuits. Logic circuitry converts the voltage originally used to activate the mechanical relay to a logic signal that powers the appropriate motors.


Relays Which Can Be Used on Either Type of Leslie Family

Hamptone SSR-3X

Standard cable, use fast stop slow switching method, not compatible with stock Leslies. Switching kit for 122 type (8000, 6122 kit ect.) not needed. Mounting location is in place of the mechanical relay.

Switching scheme: Sinking (utilizes pin # 5 to control switching) 0V (closed) fast, open stop, 220K to Ground is slow.

Vendor comments

The Hamptone SSR-3X was especially designed to turn "dual-speed" Leslie speakers into a 3-speed off/slow/fast unit using a single 3-way switch. This is accomplished by referencing the signal wire to ground. No more high voltage AC switching (147 type) or DC (122 type) on the audio line. When installed, the 147 series amp will stay unbalanced and the 122 series amps will stay balanced. If you need to stay compatible with other stock 122 or 147 series amplifiers, choose one of our other solid-state relays. This unit works flawlessly!


RTCLogic (U-SSR)

A jumper selects 147 or 122 operation. And supports the EIS stop mode switching in both cases. Onboard logic power supply - does not use the filament supply from the amp. A second jumper selects between the coast or braking mode. All software based. Three visual indicators (LED'S) indicate power and speed status. Eliminates the 12AU7 switching tube in the 122 family. The .1mfd cap removal is required. Mounting location is in place of the mechanical relay.

Switching scheme: Sourcing (Standard), 0-8.5 VDC fast, >13.5VDC slow, and 8.5-13.5VDC stop.

Vendor comments

Easy installation, vendors need to stock one part.

As of late August 2008, the originating inventor passed away. This product might not be available unless someone takes on the business. A future update is possible.

UPDATE 9/01/11 This product is going back into production with improved software. We are in the testing stages and will have them available in the fourth quarter of 2011. www.bentonelectronics.com/news.html Stay tuned!


Speakeasy Vintage Music Universal Solid State Relay (USSR)

A slick little device that can be utilized with the 147 type or the 122 type Leslies. No jumpers or software to worry about. This unit uses the switching tube in the 122 to maintain original 122 switching characteristics. Also the switching is accomplished with current not voltage like the other SSR's, eliminating possible stop state when passing through that 12 VDC region (slow to fast) of some other solid state devices.

Vendor comments

With care an attention to detail, we have created a solid state relay that is silent, reliable, and works in both 147 (110VAC) and 122 (80VDC) applications. Now, one part can work in either system. Pre-attached wires match the original Leslie color codes and can be installed in minutes.


?ISI Controls (ISI Controls)

ISI Controls features as follows:

  1. Balanced / unbalanced outputs.
  2. Low voltage control switching (under 20v). It can use a half moon switch or a foot switch.
  3. Three positions, fast, slow and off. Allows the off from either fast or slow, (with brake (RTC) or non brake RTC & Carribean). i.e. Booker .T type coast.
  4. Single family or multi-family simultaneous switching using a single switch. The switch is removable on road units.
  5. Control 6 pin Leslies (with ISI relays), 9 and 11 pin Leslies simultaneously with one switch.
  6. Controls dual motor stack Leslies and single motor Leslies equipped with Carribean and or RTC Logic motor controllers.
  7. 25 amp solid state relays, zero crossing switching.
  8. No speed switching lag on 6H (122 type) Leslies.
  9. Optional m-e-e module can control any Leslie combination with Hammond cab, balanced and unbalanced. Some units derive power from speed control supply.
  10. ISI can control up to 15 Leslies with an AC relay, more upon special order.
  11. ISI is compatible with all Hammond tone cabinets.
  12. ISI provides interchangeability for the 122 &147 when all are ISI equipped.
  13. Not compatible with stock Leslie 6 pin AC speed switching. It is purposely done to keep dangerous voltages away from the player’s hands.
  14. Custom designs upon request.

An ISI Controls unit and bipolar power supply has to be installed in the organ and a relay in 6 pin Leslies. 9 and 11 pin Leslies remain stock. The supply and control unit goes in the console, the relays under the 6 pin Leslie amp. No additional cabling is needed. It uses pin 5 in the 6 pin Leslie cable and keeps 9 & 11 pin cables stock. Kieth H. Clark is the inventor and originator of the line. The ISI Controls is a whole system. It is not a single component replacement. The system needs a bipolar supply to power the 12V low voltage control relays providing the controlling signals (12V, 0V & -12V) to the solid state relay mounted in the Leslie 6 pin amplifier’s, thus keeping line voltage out of the half moon or footswitch.

Vendor comments

The Patent Pending ISI Controls unit is compatible with all stock 9 & 11 pin Leslies and all ISI 6 pin equipped, whether 147 or 122 types. The system also works with motor controllers such as the Carribean controls unit and a special version of the RTC logic unit. You can build your system with 122 types, 147 types, 21H types 9 and 11 pin types, all simultaneously controlled. ISI Controls is NOT compatible with 122,147 or 251 stock switching.

It is this way for a reason. After long deliberation and consideration the path chosen was a clean sheet of paper in the design phase to correct all shortcomings in the original Leslie switching designs. It is a totally new standard. It eliminates failures in the 122 type, relays, faults in the B+ for switching. Also eliminates capacitors in the audio line to cabinets. It eliminates AC in the switching controls and associated lines with their hazards in the 147 application. Trying to keep the old system with workarounds is just a band-aid to cure the old ills. Remember, Don Leslie had no idea that people would be connecting all types of Leslies in all different applications, that is entirely opposite of his intentions.

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